Dust separator



March 29, 1932. MOD, DUCKHAM 1,851,819

DUST SEPARATOR Filed Feb. 3, 1928 2 Sheets-Sheet 1 Patented -Mar.- 29, 1932 UNITED STATES;

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ARTHUR MCDOUGALL nucxnm, on'mmmnNGLAm) mrsr SEPABATQR Application fil ed February 3, 192a, SerialNo. 251,661, and in Great Britain ha s. i927.

This invention relates to improvements in the separation or grading of solid materials by the action of an air blast. In someapparatus for this purpose it is the intention 6 that the lighter constituents of the material to be separated or graded shall be borne'on' practice to provide large dust catching chambers above the separating device.

The invention improves such dust catching chambers with a view to ensuring a better deposition of dust therein, so that the air which is returned to the fan to avoid pollution of the atmosphere shall enter the fan *as free as may be from suspended matter, thus prolonging the life of the fan.

The chamber is constructed in such a man .ner that the air which has passed the grading' device and has become laden with fine material, flows into the chamber with considerable velocity, which is then rapidly diminished, whereafter the air is caused to travel in the chamber, past the dust pockets, in a stream line flow, that is to say without.

any sudden change of direction, until its speed is again increased and subsequently diminished. Such alternate variation of speed with maintenance of stream line flow may be repeated several times, although one repetition generally suflices.

The intake of the fan is connected with the upper part of the chamber and in leaving the 40, latter the air reverses its direction.

Owing to this construction the air travels in the chamber with minimum formation of vortex so that there is little tendency for settled dust to be picked up or for suspended dust to remain in suspension.

Fig. 2is a section on line 22 of Fig. 1

F i'g. 3. is a view form, and

Fig. 4 is a sectionon line 44 of Fig. 3.

similar to 1,015 another -f Referring to Figs. 1 and'2, the fan a discharges airthrou-gh the pneumatic separating. device. 0 at the. bottom of the chamber 1). The device. 0 may be of any kind but is here represented. as of the kind comprising reciprocating screening table along which the coarse material travels owing to the reciprocating movement, while the fine material is takenup by the air; The passage d into the chamber is comparativelyfnarrow and dust pockets e are formed on each side of it from these pocketsv the dust 'is removed by screw conveyors The main body of the chamber is'of cross section considerably wider than that ofthe passage d, but is contracted at its upper part by bafileyplate g.

Thesemay be hinged to the sides of the chamavoid serious variation of pressure inthe chamber. .To avoid as; far as possible deposition of dust inthe suction pocketsformed by plates 'g, hinged flaps is capable of being fixed at any suitable angle are provided. The air is rapidly expanded as it passes from passage d into the chamber and is gradually compressedas it leaves the chamber until it expands again in the cover, where it re-- verses its directon of flow in order to return to the fan.

In Figs. 3 and 4 the construction is generally similar tothat shown in Figs. land 2, but the off-takes h to the fan are along the middleline of the chamber. The bafiles g are hinged on longitudinal bars spaced a short distance from the sides of the chamber to permit passage of dust down the sides, and are made in parts adapted to slide on each other so that the extent to which the bafile projects into the chamber may be adjusted.

So also the slides of the passage d are made in parts adapted to slide on each otheroso that the path of travel of the air before it is expanded may be varied in length. The cover k is not normally open to the air, but slots Z are provided which can be more or less closed by adjustable slides. 7

. Having thus described'the nature of my said invention and the best means I know of carrying the same into practical effect, I

claim I a 1. A dust catching chamber for pneumatic separation apparatus, including a chamber having apassage through which air enters the chamber, which passage is of consider ably smaller cross section than that of the chamber and has walls extending into the chamber, baifies extending from the sides of the chamber towards the middle thereof at a level abovethe outlet of said passage and terminating short of the planes in which the walls of the-passage would'lie if produced, oif-takes from the chamber beyond the said bafiles, and a cover for said chamber forming with said bafiles a second chamber in which theair expands after it has passed the said bafiles.

2. A dust catching chamber for pneumatic separation apparatus, including a chamber having a passage through Which'air enters the chamber, which passage is of considerably smaller cross section than that of the chamber and has walls extending into the chamber, bafiles extending from the sides of the chamber towards the middlethereof at a level above the outlet of thesaid passage and terminating short of the planes in which the walls of the passage would lie if produced, ofi'takes from the chamber beyond the said baflles,said oil'takes being disposed within the chamber and along the middle line of the chamber, and a cover for the chamberforming with the said baflles a second chamber in V which the air expands after it has passed the said bafiles. V V r In testimony whereof I have signed my name to this specification. V

' ARTHUR MCDOUGALL, DUCKHAM. 

